Selective discharge control for inks



April 3, 1951 w. c. HUEBNER 3 SELECTIVE DISCHARGE CONTROL FOR INKS ONPRINTING PRESSES 6 Sheets-Sheet 1 Filed Aug. 6, 1945 INVENTEIR f/uEB/VER ATTORNEY April 3, 1951 w. c. HU'EBNER SELECTIVE DISCHARGE CONTROLFOR INKS 0N PRINTING PRESSES 6 Sheets-Sheet 2 Filed Aug.' 6, 1945INVENTOR 1.1.14 C. H EBA/Efl mRNEY u l l l l h l 4 April 3, 1951 w. c. uBNER 2547 706 SELECTIVE DISCHMEEEEIONTROL- FOR INKS ON PRINTING PRESSESFiled Aug. 6, 1945 6 Sheets-Sheet 4 INVENTOR. W121 mM 6'. /uea/vse 1Mmiem z gm 4 rrae/ve Y5 April 3, 195fi w. c. HUEBNER SELECTIVE DISCHARGECONTROL FOR INKS ON PRINTING PRESSES Filed Aug. 6, 1945 6 Sheets-Sheet 5INVENTOR. Wu. 4 mm C Haas/wee BY April 1951 w. c. HUEBNER 2,547,706

SELECTIVE DISCHARGE CONTROL FOR INKS ON PRINTING PRESSES Filed Aug. 6,1945 6 Sheets-Sheet 6 INVENTOR. W/LL/AM 6. Hues/wee A ram/vex:

l aten tecl Apr. 3, i951 OFFICE SELECTIVE DISCHARGE CONTROL FOR INKS ONPRINTING PRESSES William 0. Huebner, New York, N. Y. Application August6, 1945, Serial No. 609,269.

This invention relates to a process and apparatus for printing and moreparticularly to the method and means for selectively controlling thedensity or color value-of the ink deposition on the print receivingmaterial.

This application is a continuation-in-part of my application Serial No.530,787, filed April 13, 1944, for Means and Method of Selective Controlof Ink Deposition in Printing, and abandoned September 13, 1945.

The sense in which certain terms are employed herein is set forth at theoutset to clarify the statement of the objects of the invention and thedescription and claims which are to follow and to avoid all likelihoodof confusion or misunderstanding.

The terms printing, electronographic printing or related terms are usedherein in the same sense as in my earlier Patents 1,820,194 of October25, 1931, and 2,224,391 of December 10, 1940, and refer to thereproduction of an image or the production of a desired design on theprint receiving material by the use of electro lines of force totransfer the ink to the print receiving material and without relying onpressure to effect such transference as is usual in ordinary pressureprinting. The terms image and design are employed as meaning letters,words, texts, illustrations, zones and all other representations, singlyor in combination, and which are ordinarily produced on print receivingmaterial in the printing art. The term print receiving material orelementrefers to paper, cloth or other textiles, metals and any othermaterial capable of having produced thereon an image or design. The termink is to be understood as including not only ink such as commonly usedin the printing art, but also pigments, coloring matter, paints and allother fiowable materials that may be employed in producing an image ordesign on print receiving material.

The expression field of force is used herein in the sense generallyemployed in writings on electrical phenomena 'to indicate the field,zone or sphere within which electrostatic forces are sufiiciently activeor powerful enough to effect a transference of ink from one surface toanother. The expression lines of force similarly is employed to indicatethe forces themselves acting in a definite path or direction ineffectingthe transference of the ink. Such lines of force are measurable indirection and amount and their effects, even though the theoretical 30Claims. (01. rol -42s) explanation of what produces these effects maynot be entirely clear or certain. v

, An object of the invention is to provide a method of and means forelectronographically printing whereby various densities or color valuesof the ink deposition can be obtained in different portions of thereproduced image on the print receiving material or whereby the inkdeposition can be controlled to produce different desired designs onsaid material.

In printing it is ordinarily and frequently necessary to apply differentdensities of ink on certain areas of the print receiving material thanon other areas thereof, that is, certain areas should be heavier or moresolid than other areas withvarying gradations between the light andheavy reproduced image areas in order to obtain commerciallysatisfactory printing. In my prior patents above referred to, thetransference of the ink to the print receiving material is effected bypassing the material through a uniform strength electro field of forceand subjecting the ink to the lines of force to effect the transferthereof. I Consequently, due to the uniform strength of the electrofield of force, the deposition of ink on the print receiving material isof substantially uniform density.

An object of the present invention therefore is toprovide improved meansand method in the art of electrostatic printing for selectively andautomatically controlling the intensity of the electro lines of force,to the end that the resulting image produced on the print receivingmaterial will have the desired density gradations of ink deposition ondifferent areas thereof.

A further object of the invention is to provide in electroncgraphicprinting apparatus improved means for varying the volume of inktransferred to the print receiving material at selected points or areasin accordance with the requirements of the image to be reproducedthereon or in accordance with the character of the design it is desiredto produce on the material.

Another object is to provide in an electronographic printing apparatus aplurality of separately and selectively controlled sets of opposed inkdischarge and attraction elements and between which elements the printreceiving material passes, whereby the volume of ink transferred to theprint receiving material at any predetermined point within the zone oftransference may be varied or controlled to meet predeterminedrequirements.

Another object is to provide an electronographic printing apparatus suchas referred to in the last named object and wherein a master controldrum is employed to automatically control the intensity of or tointerrupt the electro field of force between the discharge andattraction elements of the separate sets of elements to thus vary thedensity of the ink deposition on the various areas of the reproducedimage or to produce on the print receiving material a desired orpredetermined design.

In multicolor printing it IS desirable and commercially essential thatline uniform quality of printing be maintained throughout an entireedition. In order to obtain such fine, and form quality, the differentlycolored inks, such as yellow, red, blue, emerald green, purp e, blackand other colors should be applied accurately as to quantity or volumeif the correct balance of colors is to be obtained. It will beunderstood that should anyone of the component colors of the printedmatter be too light or too strong an adverse result maybe obtained andthe uniform quality of the edition destroyed.

An object of the invention is to provide an improved method of andapparatus for multicolor printing whereby the quantity or volume of theinks or pigments deposited upon the print receiving material is socontrolled as to result in producing the desired color values of theprinted edition with the requisite uniform quality throughout.

Another object is to control inmulticolor printing the color values overthe entire width of the print receiving material whereby localareas maybe accentuated where more solid color is needed for greater strength toenhance the brilliancy ofthat local area.

A general object of the invention is to provide an improved method ofand means for electronographically printing that broadens theadaptability of this art to meetrequired or desired results necessaryfor commercial printing and give to electronographic printing; anadvantageous flexibility.

Further and additional objects and advantages not hereinbefore referredto will become apparent during the detailed description of severalembodiments of the invention which is to follow.

Referring to the accompanying drawings,

Fig. 1 is a fragmentary vertical longitudinal sectional view through aprinting couple of an electronographic printing press takensubstantially on line l-l-'"of Fig. 2- and embodying one form of thepresent invention.

Fig. 2 is a vertical transverse sectional view taken substantiallyonline 2-2 of Fig. 1.

Figs. 3 and 4 are views similar to Figs. 1 and 2, respectively, butillustrating a diiferent embodiment of the? present invention.

Fig. 5 is a developed view partly in end elevation and partly in sectionof" the printing press embodyingthe invention andillustrated in Figs. 1and 2 and shows the master control; drum which is employed; in theprinting couple.

Fig. 6 is a fragmentary vertical transverse sectional view takensubstantially on line 6-6 of Fig. 5 and shows an inking roller forinking the image carrying cylinder of the couple.

Fig. '7 is a diagrammatic developed view of a portion of thecircumference of the control drum shown in Figs. 5 and 6 and takensubstantially on line I -l of-Fig. 9 and also of the control circuit forone set ofopposed discharge and attraction elementscarried,respectively, by the image cylinder and the supporting cylinderof the printing couple.

Fig. 8 is a view of a portion of the control drum and control switchshown in Fig. '7 and is taken looking from the right hand side of Fig. 7with the support for the control switch shown in section.

Fig. 9 is a developed fragmentary elevational view of a portion of thecircumference of the control drum shown in Figs. 5 and 6 and illustratesthe various positions assumed by the control switch actuating lever asthe drum rotates.

Fig. 10 is a diagrammatic illustration indicating by dash lines theareas of the print receiving material on which the ink depositions aremade under the control of the portion of the control drum shown in Fig.9 and correlated to the different positions of the switch actuatinglever shown in. Fig. 9.

Figs. 11 and 12 are similar to Figs. 9 and 10, respectively, butillustrate a different portion of the control drum circumference and theform of design produced by said portion.

Fig. 13 is a developed partial end elevational and sectional view of theprinting couple disclosed in Figs. 3 and 4 and has added thereto themaster control drum and other elements of the control mechanism forcontrolling. the intensities of the electrostatic fields of forcebetween the discharge and attraction elements or blades of the separatesets of elements or blades.

Fig, 14 is a fragmentary vertical transverse sectional view takensubstantially on line Hi -4'4; of Fig. 13 looking in the direction ofthe arrows. Fig. 15 is a diagrammatic illustration of the electricalcontrol means employed in the embodi-- ment of the invention shown inFigs. 13. and 14.

Fig. 15a is a diagram of portions of an electrical control circuitsimilar to Fig. I5 but showing a modified form of control, and

Fig. 16 is a detached detail view looking at the slotted'end of one ofthe-cylinders containing the light sourcein the control mechanism.

Inasmuch as'the present invention maybe incorporated in single ormultipleunit presses; in sheet or web presses, with relief, intaglio orplanogr-aphic printing plates, all as shown in my: sa-id prior Patentsthe-discharge and attraction elements disclosed in. said applications.are each in the form of asingle element extending the-longitudinallength of: the respective cylinder within which it is mounted, whileinthe construction shown herein in Figs. 1 and 2 the opposed dischargeand attraction elements: are arranged? in a multiplicity of separate orindependent sets of. elements zlocated'i within the respectivecylinders.

Referring now to'Figs 1. and 2, the vertical;

members of a press frame are indicatedat Ill and non-rotatable sleeves Hare supported in said members. Collars 12, are mounted onthe inner endsof the sleeves, H. and. said collars support antifriction bearings IS.The bearings, l3 rotatably support disks It which form the opposite,ends of the image carrying,w cylinder A andthe. supporting cylinder 13.The disks I4 arepro videdon their circumferences with gears l5with1,820,194 and 2,224,391, it is: deemed necessary to illustrate onlyasingleprintmeans such as the dowel pin [8. The image or plate carryingcylinder A and the supporting cylinder B are mounted on the insulatingrings l6 and hence are electrically insulated from the disks [4.

The image cylinder A may be provided with a printing plate of therelief, intaglio or planographic type as desired, or it may be providedwith image portions permeable to electro lines of force and non-imageportions impermeable thereto all as disclosed in my said prior Patent2,224,391. Also the cylinder A may be a plain cylinder in thoseinstances wherein the transference of ink to the print receivingmaterial to produce a desired design is controlled solely by theexistence or non-existence of electro fields of force between the pairsof discharge and attraction elements, as will later be pointed out.

The cylinder A can be inked in any of the known and usual ways,depending upon the type of printing plate used, one such way of inkingthe cylinder being indicated in Fig. 6 by the inking roll l1.

The lower or supporting cylinder B will have a smooth plain surface andits function is to sup-- port the print receiving material directly, as

shown in my said Patent 2,408,1 i3, or to support a feed belt (not shownin Figs. 1 and 2 but shown in Figs. 3 and 4) which in turn supports theprint receiving material.

As described in my prior patents hereinbefore referred to, the electrolines of force passing between the discharge and attraction blades orelements, later to be described and located within the cylinders A andB, respectively, act to transfer the ink from the image areas of thecylinder onto the print receiving material passing between the cylindersA and B and moving in timed relation thereto.

Extending through the center of each of the cylinders A and B is ahollow insulator tube 38, supported in the sleeves I I. Straddling eachtube 38 at relatively closely spaced intervals substantially the lengthof each cylinder is a series of U- shaped magnet cores 39. These magnetcores are centered by and slidable with respect to the correspondingtube 38 and are adjustable radially of the cylinders by means of theadjusting screws 3| which are swiveled in a supporting plate idsupported in turn by the tube 38. Each magnet core 39 is provided withright and left windings or spools 42 and all of the windings or spoolsare connected to a suitable source of electric current as will be wellunderstood and as is disclosed in my hereinbefore mentioned Patent2,224,391.

Although the magnet windings in both cylinders A and B are stated atthis time to be connected to the same source of electric current, itwill be pointed out hereinafter that the magnet windings in cylinder Aneed not be energized while the separate magnet windings in thesupporting cylinder B can be variably energized to create magneticfields of different intensities which will act to transfer the ink fromthe printing cylinder A to the print receiving material in such manneras to produce ink deposition oi? various densities on the material.

As shown in Fig. 2 the magnet spools in cylinder A are aligned with themagnet spools in cylinder B and are arranged in vertical pairs with anorth pole or spool in the cylinder A disposed opposite a south pole orspool in the cylinder B, and correspondingly a south pole or spool ofcylinder A opposite a north pole or spool of cylinder B.

Specially shaped field bars-44 are secured to the ends of the respectivesets of ends of the magnet cores 39 and are provided with arcuate outersurfaces 45 disposed closely adjacent the inner surface of thecorresponding cylinder with the respective adjacent edges of the fieldbars located closely together along a line extending lengthwise of thecylinders.

Y Secured to the insulator tube A andarranged lengthwise of said tube isa series of slightly separated relatively narrow blade sections orsegments constituting separate discharge elements. Similarly the tube 38in the supporting cylinder B is provided with a series of slightlyseparated relatively narrow blade sections or segments 41- constitutingseparate attraction elements. Said blade sections extend radially of therespective cylinders and have in this instance sharp or knife-like edgesdisposed opposite each other and as shown terminating closely adjacentthe inner surfaces of the respective cylinders at the printing zone, itbeing remembered that the two cylinders are slightly spaced apart sothat there is no mechanical pressure or contact between the cylindersand in the illustration no mechanical pressure or contact between thecylinder A and the print receiving material 25 when the latter ispassing between the cylinders.

It will be understood that the width of the blades 35 and ll andtherefore the number of said blades may be varied in accordance with thenature of the printing to be produced on the print receiving material.

Also secured to each of the insulator tubes 3 and extending radiallytherefrom on each side of the respective sectional or segmental blades35 and 41 between said blades and corresponding magnet spools areinsulating shields or plates 10 which-extend throughout the length ofthe series of blades.

The blade sections or segments are each electrically connected with anindependent wire or conductor 49 and all of said wires or conductors fora set or series of the blades will lead to the exterior ofthe cylinderthrough the insulator tube 38. The respective sets of conductors areconnected to acontrol mechanism one form of which is illustrated inFigs. 6 to 12 inclusive and will later be explained.

As clearly explained in my prior Patents 1,820,194 and 2,224,391 thedischarge and attraction elements, 1. e., the blades, when connectedwith a source of high potential electric energy, produce an electrofield of force extending between theelements and acting to transfer theink from the cylinder A to the print receiving material. As alreadystated, the magnet spools or windings are so arranged that north andsouth poles are disposed radially opposite each other in the twocylinders. With this arrangement the magnetic lines of force parallelthose of the electronographic lines of force and in close proximitythereto and form shields on each side of the electronographic lines offorce, thus preventing 38 in the cylinder I arrives J? or at leastminimizing any tendency to spread or disperse that the electronographiclines of force might otherwise have and thereby insuring a more sharplydefined and clear out reproduction of the image on the print receivingmaterial.

The insulator shields I serve both to prevent dissipation of theelectrical energy supplied to the discharge and attraction blades orelements and to prevent the magnetic fields from distorting theelectronographic fields of force. Where relatively high voltages areused to supply the attraction and discharge blades and particularly whenthe magnetic field is employed, the insulator shields I0 will preferablybe used as shown and described. However, the magnets may be omitted insome instances and in such case the insulator shields may also beomitted.

In commercial printing, as previously mentioned, certain portions of thereproduction may require a greater or heavier concentration ordeposition of ink than other areas thereof consequently it is proposedto vary the voltages of the currents supplied to the different sets ordischarge and attraction blades and 41 in correlation to the densitiesof the ink deposition to be made on the print receiving material.Inasmuch as the width of the blades of the sets of blades is relativelynarrow various relatively narrow fields of force of differentintensities can'be produced thus providing selective control of thedeposition of the ink when actual printing of texts on irregular imagesis being performed or spot or area control when the deposition of ink isto produce a desired design and the ink has been applied over the entiresurface of the cylinder A. Although the blades of each series are shownas slightly spaced apart, it will be understood. that the transferredink will have a certain spread and the printing produced will notindicate the spaces shown between the blades.

A mechanism for controlling the intensities of the fields of forceproduced by the sets of discharge and attraction elements will now beexplained with particular referenc'e'to Figs. 5 to 12 inclusive. Aspreviously stated, the gears (*5 of the cylinder Bmesh with drivinggears and reference to Fig. 5 discloses said driving gears 19 as mountedon a driving shaft 2|) thatis. actuated by asuitable power source notshown; The frame members Ill rotatablysupport belowthe shaft '20 amaster control drum 2| which is provided on its opposite ends with gears22 that constantlymesh with the gears I9. Although the axis-of thecontrol drum is shown in vertical alignment with'tlre axes of thecylinders A and B and shaft 20; 'it will be understood that thisrelationship can-be varied if desired, as, for instance, to reduce theheight of the press. The cylinders A andB and the drum 2| rotate intimed relation to each: other with the cylinder A rotating in acounterclocke wise direction as viewed in Fig. 6- and. the cylinder Band drum 2| in a clockwise direction.

The drum 2| is divided longitudinally thereof into zones correlated innumber to the sets of discharge and attraction-elements in. thecylinders A and B. Each zone of the drum-2| is in the formof a' circulargroove: formed in the drum and is provided with a seriesoficircumierentially spaced openings 23. The openings 23-arez adaptedto'receive pins formed on cam blocks: Zeandsa-id pins areheld' intheholes 23 inany'd'esired' orwell known manner. The cam blocks 2 t'are'ofsuch width that they'interfit the z'onegrooves-andzconsequently are heldagainstturning movement (see Figs. Tami 8). Thet'difier-entz caml'blocks2'4rare provided with different shaped camming portions and said camblocks are mounted in the zone grooves in correlation to the image thatis to be reproduced on the print receiving material or to a desireddesign that is to be produced thereon, as will later be readilyunderstood.

A supporting bar 25 i carried by the frame members H1 and extendslongitudinally of the control drum 2! and carries a series of controlswitches '26, there being as many control switches as there are groovedzones on the drum 2|, see Fig. 5.

The control switches 26 are illustrated merely by way of example ashaving two on positions and an intermediate or off position, it beingunderstood that a different form of switch might be employed if desiredto meet certain conditions. The switch 26 is illustrated as comprisingtwo spaced contacts 21 and 28 and an arcuate wiper contact 29'. A switchbar 30 is constantly in contact with the wiper 29 and can be selectivelyen'- gaged with the contacts 21 or 28 or can be positioned intermediatesaid contacts 21 and 28 when the switch is in its off position.

The switch bar 38 is insulated from but carried by a rockable lever arm32 that is pivotally mounted on the support 25 and extends radiallytoward the control drum 2| as viewed in Figs. 6 and 8, with the end ofthe lever arm cooperating with the cam block '24. It will be seen thatas the control drum 2| rotates and the lever arm 32 comes intoengagement with one of the cam blocks 24 said cam block can effect arocking movement of the lever arm to position the switch plate 30 ineither one of the two on positions or in the intermediate on osition.

Each attractionblade 41 is electrically connected by a wire 33 to thewiper contact 29 of its correlated switch 25 as clearly shown in Fig.'7. Each discharge element 35 is electrically connected by a wire 34 toone side of a source of high potential-electric energy. The other sideof said source of electric energy is represented by the wire 36 which iselectrically connected to the adj us'table wiper arms 37 of a pair ofrheostats 4| and 43. The resistance 46 of the rheostat 4| iselectrically connected by a wire 48 to the contact 28 of the switch 26.The resistance 50 of the rheostat 43 is electrically connected by'a wire5| t0 the contact 21 of the switch 26.

As shown inFig. 7 the wiper arm 31 of the rheostat 4| is positioned tocut out the resistance 46 from the circuit, wherefore said resistancedoes not reduce the intensity or the current in the circuit in thisinstance and full source current can pass between the discharge andattraction elements 35 and 41 when the switch bar is contacting thecontact 28.

It will also be noted by reference to Fig. 7 that the wiper arm 31' onthe rheostat 43 is positioned to include a portion of the resistance 50in the circuit between the discharge a'nd attraction elements when theswitch bar 3i? is engaging the Contact?! of the switch 28 and hence theintensity o'f the current in the-circuit will be reduced a predeterminedamount.

It will be understood that when the switch bar 30 is in the intermediateposition between the switch contacts 21- and 28 no induced current willbe flowing between the discharge and attraction elements 35and- 4'I inthis partioular instance.

Assuming that the entire exterior surface of the cylinder Ais: inked bythe inking. roller IT in a manner well known in the art and that adesired design is to be produced on the print receiving material 25 thecam blocks 24 correlated to each set of discharge and attractionelements are positioned in a predetermined manner circumferentially ofthe drum to control the circuits to the respective sets of discharge andattraction elements so as to provide in this instance a circuit of highintensity, a circuit of low intensity or to interrupt the circuit.

In Fig. 9 there is illustrated in a developed manner one groove zone ofthe control drum 2| with the cam blocks 24 arranged therein in saidpredetermined manner. Assuming that the printing couple is operating andthe control drum is rotating in the direction of the arrow in Fig. 9 andreferring to the lowermost cam block 24 in said view, it will be notedthat the end of the lever arm 32 is in its most left hand positionbefore it contacts with said lowermost cam block 24. Therefore theswitch bar 3!] is engaging the contact 28 of the switch 26 andconsequently the induced current between the discharge element 35 andthe attraction element 41 is of maximum intensity and the deposition ofink on the print receiving material at this moment will be of heavydensity or color and will produce a heavy color zone on the materialrepresented by the lowermost dash line outline of Fig. and which forillustration purposes parallels the groove control zone of Fig. 9.

As the control drum rotates in the direction of the arrow the end of thelever arm 32 engages the cam surface of the lowermost cam block and ismoved toward the right until it is in its extreme right hand position.This movement of the lever arm 32 causes the switch bar 30 to move offof the contact 28 and momentarily into a position intermediate thecontacts 28 and 21, at which time the circuit through the discharge andattraction elements is momentarily interrupted and then to move intoengagement with the contact 21,- whereupon the circuit is reestablishedbut at a lower intensity. Consequently there will be a space on theprint receiving material on which no ink deposit will be made and thenthe ink deposition will be resumed with a light deposit. During thefurther rotation of the drum the lever arm 32 stays in the position towhich it has been moved and the light deposition of ink continues to bemade on the print receiving material as indicated in Fig. 10 by theelongated dash line outline marked light. As the drum continues torotate the end of the lever arm. 32 engages the camming surface of thenext cam block 24 which is spaced circumferentially from the firstmentioned cam block and said lever arm is rocked by the second cam blockto its intermediate position, at which time the circuit to the dischargeand attraction elements is interrupted and consequently no ink depositis made on the print receiving material. As the drum 2| continues torotate the camming surface of the third circumferentially spaced camblock 24 engages the end of the leve arm 32'and moves said end of thearm from its intermediate position to its most left hand position,whereupon the switch bar 30 again engages the contact 28 and the highintensity circuit between the discharge andv attraction elements isrestored and a heavy ink deposit is now being made on the printreceiving material, as indicated by the dash line outline at the upperend of Fig. 10.

It will be understood that the camblocks can be so positioned as to varythe path which the end of the lever arm 32 will follow during therelative rotation between the drum and the lever arm so as toselectively produce predetermined heavy or light ink depositions on theprint receiving material or areas where no ink is deposited.

Figs. 9 and 10 as already explained indicate one arrangement of the camblocks for produc-. ing predetermined design of ink deposit on the printreceiving material, while Figs. 11 and 12 represent a differentarrangement which can be employed as will be clearly understood. It willbe understood that the cam blocks will be arranged in this predeterminedmanner in all of the groove Zones of the control drum so as to controlsimultaneously. the transference of ink between the discharge andattraction elements of all of the-sets of-said elements and therebyproduce the desired design on the print receiving material extending thewidth thereof.

In place of the switches 26. being of the type to provide two onpositions and an oil posi-. tion, said switches can be of dififerenttype so as to provide a different number of on and off positions asdesired according to the desired design that is to be produced on theprint receiving material but for the sake of simplicity only athree-position switch has been illustrated herein. Y

The description just above given refers to the production of a desireddesign on the print receiving material as indicated in Figs. 10 and 12and when the drum A is entirely permeable to the electro lines of force.The present invention can also be employed when the drum A is providedwith a predetermined image thatis to be reproduced on the printreceiving material as, for example, when the drum A is constructed as inmy prior Patent 2,224,391 with image areas permeable to lines of forceand non-image areas impermeable thereto. e

When a predetermined image is to be reproduced on the print receivingmaterial the intensity of the induced electro lines of force between thedischarge and attraction elements of each set can be controlled in amanner somewhat similar to that previously described herein to cause theink deposit corresponding to certain image areas or to certain portionsof certain image areas to be of different degrees of density, 1. e.,heavy, light or intermediate shades. In such case the control switchesused would have a number of positions corresponding to the number ofshades desired, it being understood that theoutline of the reproducedimage would be attainedby the outline of the permeable image portions ofthe drum. j

It will also be-understood'that thepresent invention can be employed tocontrol the color shades of the reproduced image whenthe drum A isprovided with a printing or image plate of either the intaglio, reliefor planographic type as will be apparent to one skilled in the printingart.

In describing hereinafter another embodiment of the invention a moredetailed description 'as to how the invention is adaptable forcontrolling the color shades of the reproduced image will be set forth.

Referring now to the embodiment of the invention shown in Figs. 3 and 4,the selective con trol of the intensityof the lines of force throughoutthe length of the field is illustrated as incorporated in that type ofprinting apparatus shown in mycopending application Serial No. 518,470,filed January 15 1944. now= Patent 2,451,288, wherein the ink istransferred from the discharge blade or element. directly to the .printreceiving material and withoutintervening The cylinder A application ofthe ink to an image carrying plate or surface. Also in said Patent2,451,288 the supporting cylinder for the print receiving material orthe conveyor printing cylinder and is provided with image portionspermeable to the electro lines of force and non-image portionsimpermeable thereto, wherefore the ink is transferred to the printreceiving material only in those areas correlated to the permeable imageportions of the cylinder.

'In Figs. 3 and 4 the cylinder A is the printing or image cylinder andpreferably is constructed and mounted in the frame as in the previouslydescribed construction of the cylinders A or B. is adapted to be drivenfrom any suitable source of power as by the shaft 90, pin-ions SI andgears I5, while the paper or other print receiving material 86 isconveyed by a belt 82 as in my said Patent 2,451,288.

As in the construction of the press shown in Figs. '1 and 2 theattractor blades within the cylinder A comprise a series of sections orsegments I41 with individual conductors I49 leading to the controlmechanism later to be described. As shown, the blade sections aremounted on an insulator tube 92 vertically slidably guided by andadjustable on the insulator tube I38 by means of the adjusting screwsI92, whereby the spacing between the knife edges of the sectionalattractor blades 14! and the surface of the cylinder may be regulated.The sectional discharge or repulsion blades I35 are constructedsimilarly to the attractor blades, with the individual conductors 52 forthe blade sections leading to the control mechanism later to beexplained.

A controlled and conditioned supply of ink to the discharge blades I35is provided in the following manner. If all of the discharge blades areto receive ink of the same color a longitudinally extending containerI25 may be used, with said container in turn supplied through the supplypipe I26. The container I25 may have a series of nozzles I30 projectingdownwardly from the bottom thereof and corresponding in number andcorrelated to the discharge blades I35. Each nozzle is provided with acontrol valve I3I and the ink from each nozzle is disposed on aninclined plate I and flows downwardly of the plate and onto therespective discharge blade I35. To insure a steady and uniform flowthrough the nozzles air pressure may be employed, the air being admittedto the cori-- tainer I25 through the pipe I33. Also in order to regulatethe fluidity of the ink strip electric heaters I31 may be secured to theunderside of the plates I10, as described in my said Patent 2,451,288.It will be understood that in certain instances it will be desirable tohave the different discharge blades I35 receive ink of different colorsand in such cases instead of a single container I 25 for all of thedischarge blades I35 individual containers for each discharge blade maybe employed.

I Referring now to Figs. 13 to 16 inclusive, the mechanism forselectively and automatically controlling the intensities of the fieldsof force between the opposed discharge and attraction elements of thsets of said elements will now be described. The pinions I9I mesh withgears 53 on the opposite ends of a master control drum #4 which isrotatable on a shaft 55 fixedly secured in the frame members. Althoughthe drum 54 is illustrated in Figs. 13 and 14 as in vertical alignmentwith the axis of the c linder belt acts as the image or A" and shaft itwill be understood that the axes of the drum, cylinder and shaft couldbe displaced from this vertical relationship if it: were desired tolower the height of the printing press. The control drum 54 will havesecured on its periphery by suitable means a master sheet containing achart correlated to the image to be reproduced on the print receivingmaterial. It will also be understood that where the image is reproducedin different colored ink the chart will have differently coloredportions correlated to the different colored ink containers and the setsof blades associated with said containers.

The side frame members of the printing apparatus support on oppositesides of the shaft 90 bars 56 extending between the frame members andprovided with a series of openings corresponding in number to the setsof discharge and attraction blades and with each opening aligned with arespective set of blades, as shown in Figs. 13 and 14. The openings inone of the bars 56 mount housings 51 for light sources 58 of anysuitable known form, while the openings in the other bar 56 mounthousings 59 for photoelectric cells 60. The housings 51 and 59 are inthe illustration disposed substantially at an angle of 459 to thevertical center line of the press, although they might be otherwisedisposed. The housings 51 are provided at their lower ends with coverplates having slots 6| extending dia metrally thereof parallel to theaxes of the master drum 54 and cylinder A and corresponding in length tothe width of the blade sections (see Figs. 14 and 16). The housings 59mount condensing lenses 52 which act to condense the light beamsreflected from the surface of the master sheet to the photoelectriccells 65. The light beams from the light sources striking the mastersheet correspond in width to the width of the blade sections and saidbeams are re flected in varying degrees of strength according to thedensity of color upon which they im; pinge on the master sheet.Therefore the strengths of the reflected beams acting on thephotoelectric cells are in inverse proportion is the density of thecolor on the different portionsof the master sheet by which the beamsare reflected. Therefore the intensities of the induced electro fieldsof force between the different sets of discharge and attraction bladescan be controlled in relation to the different color densities on thevarious areas of the master sheet as the sensitivity of thephotoelectric cells will effeet through an amplifying arrangement laterto be described a control of the separate electrical circuits for thesets of blades. Similar light sources and photoelectric cells areemployed which scan the ink deposit on the print receiving material andcause the strength of the light beams reflected to the photoelectriccells to be in inverse proportion to the color densities of the inkdeposited on the material. The duplicate series of light sources andphotoelectric cells are located on opposite sides of the series ofdischarge blades I35 and above the print receiving material. Thesupporting bars for the duplicate series of light sources andphotoelectric cells are indicated at 56a, while the housings thereforare indicated at 51a and59a, with the light sources indicated at 58c andthe photo- "electric cells at 60a. The housings 51a will be provided attheir lower ends with cover plates having slots Bla therein while thehousings 590. will be provided with condensing lenses 62a.

Referring to Figs. 13 and 14, containers 63 shown as located below thedrum 54 house the amplifying circuits and devices with which each set ofphotoelectric cells BI] and 60a is operatively associated, there beingone container 53 for each set of discharge and attraction blades. Theamplifying circuits referred to effect forward and reverse energizationof special split phase reversing motors t l supported by the containersexternally thereof. It will be understood that the motors 6c correspondin number to the number of opposed sets of discharge and attractionblades and that said motors are arranged for convenience in two serieswith the motors related to the even numbered sets of opposed bladeslocated on one side of the containers 63 and the motors related to theodd numbered sets of opposed blades located on the opposite side of thecontainers. Each motor shaft 65 extends upwardly and is provided with aworm 65a which meshes with a worm wheel 66 mounted on the shaft 61 of arheostat later to be referred to.

Referring to the diagrammatic showing of Fig. 15, the rheostat referredto includes a resistance 68 and a wiper hand 59 mounted on the shaft 61and contacting the resistance 68, wherefore rotation of the shaft 61 bythe motor 64 (operatively connected therewith as indicated by. dash anddot lines) varies the position of the wiper hand relative to theresistance as will be well understood. One terminal of the resistance 68is connected by a wire II to one side of a source of high potentialelectric energy, while the other side of said source is connected to theattraction blade I 41 by the wire I49 previously referred to. Thedischarge blade I35 is electrically connected by the previouslymentioned wire 52 with the wiper hand 69 of the rheostat. Consequentlythe intensity of the current in the circuit to the blades I35 and I4!can be varied by the adjustment of the wiper hand 69 and thus theintensity of the induced electrostatic field of force between saidblades can be varied to change the density of the ink deposition on theprint receiving material. It will be understood that the intensity ofthe induced field of force between each set of opposed discharge andattraction blades is similarly controlled by a rheostat actuated by amotor 64. The wires 52 and I 45 and the wires, later referred to,forming the photoelectric cell circuits extend through openings in aframe member I6 and into a cover Illa (see Fig. 13) and thence to thecontainer 63 and the rheostats.

The forward or reverse operation and the stopping of each motor 64 iscontrolled'in the manner now to be described.

The photoelectric cells 60 and 60a correlated to each set of opposeddischarge and attraction blades or elements are connected in seriesparallel to wires 12 and I3. A control tube 14 is in the direct currentcircuit indicated generally at 75 and said circuit is connected to anysuitable source of regulated voltage direct current. The wire 12 isconnected to one grid of the tube 14 while the wire 13 is connected tothe other grid of said tube. As long as the photoelectric cells 60 and60a are activated by reflected light beams of equal intensity and arethus in balance nocurrent is passing through the control tube 14 to theamplifying tubes 76 andTI. However, when the reflected light beamactivating one of the photoelectric cells is stronger-than the beamactivating the other cell then one'of the grids of of the motor 14 thecontrol tube 14 is activated more strongly than the other grid andcurrent flows from said grid through the tube 14 to an amplifying tubeconnected to the grid circuit. Consequently any unbalanced condition inthe photoelectric cells 60 and 60a will operate through the control tube14 to activate either the amplifying tube 76 or the amplifying tube 11.It will be understood that so long as the light beams reflected by themaster sheet on the control drum and by the ink deposit on the printreceiving material are of the same intensity the cells 60 and 60a are inbalance and the amplifying tubes I6 and 11 are not driven. Theamplifying tube 16 may be termed the reverse amplifying tube while thetube 1'! may be designated as the forward amplifying tube. It will befurther understood that as soon as the reflected light beams vary inintensity and create an unbalanced condition between the cells 60 and660. then either the reverse tube 16 is driven or the forward tube 11,depending upon which photoelectric cell has the stronger output.

The reverse amplifying tube 76 is connected to the primary of asaturable reactor 78 while the forward amplifying tube 11 is connectedto the primary of a saturable reactor 19. The secondaries of thereactors l8 and 19 are connected respectively to the shaded poles orwindings 80 and BI of the motor 64. These poles or windings 80 and BIact as small transformer secondaries and have voltage induced thereinfrom the field winding 83 of the motor and which winding 83 iscontinuously excited from an outside alternating current source 34. Thealternating current source 84 has the primary of a transformer 85connected thereto, while the secondary of such transformer suppliescurrent to the filaments of the tubes I4, 16 and 11.

So long as the photoelectric cells 60 and 60a are in balance and nocurrent is flowing through the control tube M to the amplifying tube 16or the amplifying tube 71 the induced voltages in the poles or windings80 and BI by the winding 83 are in balance and cause no rotation of themotor 64.. As soon as an unbalanced condition exists between thephotoelectric cells 60 and 60a and the grid of the tube 16 or the gridof the tube 11 is activated and either the reactor 78 or the reactor 19becomes active then the induced voltages in the windings or poles 80 and8! are unbalanced and a current flow takes place in one or the other ofsaid windings to effect rotation of the motor 64 in either the reverseor forward direction. As previously explained, the rotation 64 in theforward or reverse direction will act through the rheostat and wiperhand 69 to decrease or increase the current to the discharge andattraction blades I35 and I4! to thereby decrease or increase theintensity of the induced electrostatic field of force between saidblades and thus to decrease or increase the density of the ink depositon the print receiving material.

It will be understood that as soon as the density of color of the inkdeposit corresponds to the density of the color on the correlatedportion of the master sheet on the control drum the photoelectric cellsare in balance and rotation of the motor 64 ceases and no further changein the current value to the discharge and attraction blades takesplaceuntil said color densities again vary. In this way an accurate control'of the ink densities of the ink deposit on the print receiving materialis maintained and an accurate .tube H to effect reverse or control sheetis obtained on the print receiving material.

Although the series of photoelectric cells 60a.

has been illustrated and described as scanning the ink deposit on theprint receiving material, it is possible to eliminate the series ofcells 69a. and light sources therefor and rely only upon the series ofcells 60 and their light sources which scan the master sheet of thecontrol drum and commercial printing can be obtained by this modifiedarrangement.

Reference to Fig. 15a will indicate a simple way in which the controlcircuit shown in Fig. 15 could be modified to eliminate thephotoelectric cell 60a and still eifectively control the density of theink deposit on the print receiving material in correlation to the colordensities on the master sheet. In Fig. 15a a variable resistance isconnected between the wires 12 and 13 in place of the photoelectric cell60a.

The variable resistance comprises a resistance coil 60b connected to thewire 12 and a wiper hand 600 connected to the wire 13 and cooperatingwith the resistance coil Gllb. The variable resistance controls thefunction of the grid of the control tube 14 that is controlled by thephotoelectric cell iill'a in the diagram shown in Fig. 15, while thephotoelectric cell 60 in both instances controls the other grid of thecontrol tube Hi. The wiper hand 600 of the variable resistance isoperatively interlocked with the wiper hand 69 of the rheostat thatcontrols the high potential electric circuit to the discharge andattraction blades indicated by the dash and dot line in Fig. 15a,wherefore the wiper hands 69 and 600 move in unison and have inverserelative positions with respect to the resistances 68 and 60b.

When the variable resistance just described is placed in the circuitinstead of the photoelectric cell 60a the control tube 14 functions inthe same way as in the circuit shown in Fig. 15 to control the flow ofcurrent to either the reverse amplifying tube I6 or the forwardamplifying forward rotation of the motor 64. It will be seen that whenthe current value flowing through the variable resistance is in balancewith the output current value of the photoelectric cell to the motor 64is not rotating. When the reflected light beam on the photoelectric cell60 causes the output current value of said cell to be above the currentvalue flowing through the variable resistance,

the grid of the tube 14 connected with the photoelectric cellpredominates over the other grid of said tube and current flows throughthe amplifying tube 11 to effect forward rotation of the motor 64 tooperate the wiper hand 69 of the rheostat to increase the resistance andreduce the high potential electric current intensity to the dischargeand attraction blades and to cause a less dense ink deposition on theprint receiving material, it being recalled that the wiper hand 69 ismechanically interlocked with the wiper hand 60c of the variableresistance. It will be seen that the wiper hand 600 will also be movedby the rotation of the motor 64 to cut out resistance until the currentvalue flowing through the variable resistance steps up until it is inbalance with the output current value of the photoelectric cell 60,whereupon the motor stops. A similar sequence takes place when theoutput current value of the cell 60 becomes less than the current valueflowing through the variable resistance,

such condit on occurring when the reflected light beam acting on thephotoelectric cell 60 is reduced in strength. When this happens the gridof the control tube 14 connected to the variable resistance is activatedto cause current to flow through the amplifying tube 16 and effectreverse rotation of the motor 61; to move the wiper hand 69 of therheostat to cut out resistance and thus to increase the intensity of thehigh potential electric current to the discharge and attraction bladesto effect a heavier deposition of ink on the print receiving material.Simultaneously with the movement of the wiper hand 69 the wiper hand (Weof the variable resistance moves to increase the resistance and thusdecrease the current value flowing to the grid of the tube 14 connectedwith said resistance until said grid is in balance with the gridconnected to the photoelectric cell Bil, whereupon the rotation of themotor 64 terminates.

From the foregoing explanation in connection with Fig. 15a it will beseen that the one series of photoelectric cells scanning the mastersheet on the control drum can effectively control the deposition of inkon the print receiving material in coordination with the color values onthe master sheet.

As previously stated herein the magnets in the cylinder A of Figs. 1 and2 could be eliminated and the magnets in cylinder 13 utilized to producemagnetic fields of force acting to transfer the ink from the cylinder Ato the print receiving material as fully disclosed in my said Patent2,224,391. It will be clearly understood that the individualelectromagnets in the cylinder B as shown in Figs. 1, 2 and 6 each couldbe connected by a separate circuit to a source of electrical energy andthat the current value of each of such circuits could be controlled tocreate magnetic fields of varying intensities to control the densitiesof the ink deposition on the print receiving material. The control ofthe current values of these separate circuits could be carried out inways similar to the methods disclosed herein for controlling theintensities of the electrostatic fields of force between the dischargeand attraction blades as will be clear to one skilled in the art.

Therefore the present invention contemplates printing by means of aplurality of separate magnetic fields of force the intensities of whichare automatically controlled to produce ink deposits on the printreceiving material of predetermined densities.

From the foregoing description it will have been seen that an extremelyflexible and efficient printing couple results from the use of thepresent invention and one wherein the volume of ink transferred by theelectro fields of force can be controlled to produce ink deposits ofpredetermined densities on the print receiving material. It will also benoted that the present invention lends itself admirably to a singleprinting couple capable of producing multicolor printing and wherein thedesired and necessary color values can be maintained throughout anentire edition.

Although a number of embodiments of the invention have been illustratedand described herein it will be understood that the invention issusceptible of various modifications and adaptations within the scope ofthe appended claims.

Having thus described my invention, I claim:

1. A method of printing by utilizing an electro field of force and whichcomprises passing print receiving material through a printing zone andmoving a master chart in timed relation to said l7- material, producingby means of an applied electric current a field of force at the printingzone with the lines of force directed to transfer ink from an ink supplyto said material, and varying said current to vary the intensity of saidfield of force in correlation to said master chart as said materialmoves through said zone to predeterminately vary the densities of theink deposits on different areas of said material to produce a printedimage or design having varying color shades or densities on diiferentportions thereof as indicated by said master chart.

v 2. A method of printing by utilizing an electro field of force whichcomprises passing print receiving material through a printing zone andmoving a master chart in timed relation to sa d material, producing bymeans of applied electric currents a plurality of separate fields offorce at the printing zone and extending transversely of said materialwith the lines of force of each field of force directed .to transfer inkfrom an ink supply to said material, and varying said currents to varythe intensities of said separate fields of force in correlation to saidmaster chart as said material moves through said zone topredeterminately vary the densities of the ink deposits on differentareas of said material to produce a printed image or design havingvarying densities or varying color effects on different portions thereofas indicated by said master chart.

3. A method of printing by utilizing an electro field of force and whichcomprises passin print receiving material through a printing zone andmoving a master chart in timed relation to said material, producing bymeans of an applied electric current a field of force at the printingzone with the lines of force directed to transfer ink from an ink supplyto said material, and maintaining the densities of the ink deposits ondifferent areas of said material in balance with .the color densities ondifferent areas of said chart correlated thereto by varying said current.to vary the intensity of said field of force.

4, A method of printing by utilizing an electro .field of force andwhich comprises passing print receiving material through a printing zoneand' 'field of force which comprises passing print re- -Q ceivingmaterial through a printing zone, and movin a master chart in timedrelation to said material, producin by means of applied electriccurrents a plurality of separate fields of force w at the printing zoneand extending transversely of said material with the lines of force ofeach field of force directed to transfer ink from an :ink supply to saidmaterial, and maintaining the densities of the ink deposits on differentareas of said material in balance with the color densities on differentareas of said chart correlated thereto by varying said currents to varythe intensities of said separate fields of force.

5. A method of printing by utilizing an electro field of force whichcomprises passing print re-- ceiving material through a printing zoneand .moving a master chart in timed relation to said material, producinga plurality of separate electrostatic fields of force at the printingzone and extending transversely of said material with the U lines offorce of each field of force directed to transfer ink from an ink supplyto said material, and varying the intensities of said separate fields:of force in correlation to said master chart as said material movesthrough said zone to predeterminately vary the densities of the inkdeposits'on different areas of said material to pro- --duce a printedimage or design having varying densities or varying color eifects ondifferent 18 portions thereof as indicated by said master chart;

6. A method of printing by utilizing an electro of force and whichcomprises passing print receiving material through a printing zone andmoving master control means in timed relat on to said material, producinby means of an applied electric current a field of force at the print.-in zone bridging a predetermined gap with the lines of force directed totransfer ink across said gap-from an ink supply to said material, andvarying said current to vary the intensity of said field of force incorrelation to said control means as said material moves through saidzone to predeterminedly vary the densities of the ink deposits ondifferent areas of said material to produce a printed image or designhaving varying COiOl shades or densities on difierent portions thereofand correlated to said control means.

r 7. A method of printing by utilizing an electro eld of force whichcomprises passing print receivin material through a printing zone andmoving a master control means in timed relation to said material,producin by means of applied electric currents a plurality of separatefields of force at the printing zone and extending transversely of saidmaterial with the lines of force of each field of force directed totransfer {design having varying densities or varying color effects ondifferent portions thereof and correlated to said control means. 7 r

8. A method of printing by utilizing an electro moving a master controlmeans in timed relation to said material, producing by means of anapplied high potential electric current an electrostatic field of forceat the printing zone with the lines of force directed to transfer inkfrom an ink supply to said material, and varying the potential of saidcurrent to vary the intensity of said field of force as said materialmoves through said zone and in correlation to said control means topredeterminedly vary the densities of the ink de-- posits ondifferentareas of said material to produce a printed image or design havingvarying color shades or densities on different portions 7 thereof.

9. YA method of printingiby utilizing an electro field of force whichcomprises passing print receiving material through a printing zone and,

moving a master control means in timed relation tosaidmaterial,producing by means of applied high potential electric currents aplurality of separate electrostatic fields of force at the printing zoneand extending transversely of said material with the lines of force ofeach field of force directecl to transfer ink from an ink supply to saidmaterial, and varying the potentials of said currents to vary theintensities of said separate fields of force in correlation to saidcontrol means as said material moves through said zone topredeterminedly vary the densities of the ink deposits on diiferentareas of printed image or design having varying densities or varyingcolor efiects on different portions thereof.

said material to produce a 10. A method of printing by utilizing anelectro field of force which comprises passing print rec'e'ivingmaterial through a printing zone and moving a master control means intimed relation with said material, producing by means of applied highpotential electric currents a plurality of separate electrostatic fieldsof force at the printing zone extending transversely of said materialwith the lines of force of each field of force directed to transfer inkfrom an ink supply to said material, restricting the effective width ofsaid fields of force by producing magnetic fields of force closelyadjacent to and paralleling each side of said electrostatic fields offorce, and varying the potentials of said currents to vary theintensities of said separate electrostatic fields of force incorrelation to said control means as said material moves through saidzone to predeterminedly vary the densities of the ink areas of saidmaterial to produce a printed image or design having varying densitiesor color efiects on different portions thereof.

ll. In a printing couple, ink carrying means, means for moving printreceiving material rela- .tive to said ink carrying means and throughthe printing zone, means for producing by an electric current an electrofield of force at the printing zone with the lines of force thereofacting in a direction to transfer ink from said ink carrying means tosaid material, and means correlated to the movement of said material forautomatically varying said current to vary the intensity of said fieldof force as said material moves through the printing zone to produce inkdeposits on said material of predetermined varying densities.

12. In a printing couple, ink carrying means, means for moving printreceiving material relative to said ink carrying means and through theprinting zone, a plurality of means for producing by electric currentsseparate electro fiields of force at the printing zone, with the linesof force of each of said fields of force acting in a direction totransfer ink from said ink carrying means to said material, and separatemeans correlated to the movement of said material for automaticallyindividually varying said currents to vary the intensities of each ofsaid fields of force as said material moves through the printing zone toproduce ink deposits on said material of predetermined varyingdensities.

13. In a printing couple, ink carrying means, means for moving printreceiving material relative to said ink carrying means and through theprinting-zone, a master control member movable in timed relation to themovement of said material through the printing zone, means for producingby an electriccurrent an electro field of force at the printing zonewith the lines of force thereof acting in a direction to transfer inkfrom said ink carrying means to said material, and means operativelycontrolled by said control member for varying said current to vary theintensity of said field of force as said material moves.

through the printing zone toproduce ink deposits on said material ofpredetermined varying density and correlated to said control member.

14. In a printing couple, ink carrying means,

means for moving print receiving material relative to said ink carryingmeans and through the printing zone, a master control member movable intimed relation to the movement of said material through the printingzone, a plurality of separate meansfo'r producing separate electrofields of force at the printing zone with the lines of force of eachfield of force acting in a direction to deposits on different transferink from said ink carrying means to said material, and separate meansoperatively controlled by said control member for varying theintensities of said separate fields of force as said material movesthrough the printing zone to produce ink deposits on said material ofpredetermined varying densities correlated to said control member.

15. In a printing couple, ink carrying means, means for moving printreceiving material relative to said ink carrying means and through theprinting zone, a master control member movable in timed relation to themovement of said material through the printing zone, means for producingby an electric current an electrostatic field of force at the printingzone with the lines of force thereof acting in a direction to transferink from said ink carrying means to said material, and means operativelycontrolled by said control member for varying said current to vary theintensity of said field of force as said material moves through theprinting zone to produce ink deposits on said material of predeterminedvarying densities correlated to said control member.

16. In a printing couple, ink carrying means, means for moving printreceiving material relative to said ink carrying means and through theprinting zone, a master control member movable in timed relation to themovement of said material through the printing zone, separate means forproducing a plurality of separate electrostatic fields of force at theprinting zone with the lines of force of each field of force acting in adirection to transfer ink from said ink carrying means to said material,and separate means operatively controlled by said control member forvarying the intensity of each of said fields of force as said materialmoves through the printing zone to produce ink deposits on said materialof predetermined varying densities.

17. In a printing couple, ink carrying means, means for moving printreceiving material relative to said ink carrying means and through theprinting zone, separate means for producing by electric currents aplurality of separate electro magnetic fields of force at the printingzone with the lines of force of said field of force acting in adirection to transfer ink from said ink carrying means to said material,and means correlated to the movement of said material for automaticallyvarying said currents to vary the intensities of said fields of force as'said material moves through the printing zone to produce ink depositson said material of predetermined varying densities.

18. In a printing couple, ink carrying means, means for moving printreceiving material relative to said ink carrying means and through theprinting zone, separate means for producing by electric currents aplurality of separate electrostatic fields of force at the printing zonewith the lines of force of said fields of force acting in a direction totransfer ink from said ink carrying means to said material, meansfor'producing magnetic fields of force on each side of saidelectrostatic fields of force to prevent dispersion of the latter and toconfine the'same to'theprinting zone, and separate means movable in'correlation to the movement of said material for automatically varyingsaid currents to vary'the intensities of each of said electrostaticfields 'of force as said material moves through the printing zone toproduce ink deposits on said material of predetermined varyingdensities.

l tions of said member determined varying densities can be made saidmaterial, in timed relation with said movable member and and includingspaced having image portions adapted to be inked, means for moving printreceiving material in operative and timed relation to said member andthrough the printing zone, means for producing by an electric current anelectro field of force at the printing zone with the lines of force ofsaid field of force acting in a direction to transfer ink from saidimage portions of said member to said material, and means correlated tothe movement of said material for automaticallyv varying said current tovary the intensity of said electro field of force as said material movesthrough the printing zone, whereby the ink deposits on said material maybe of predetermined varying densities.

20. In a printing couple, a printing member having image portionsadapted to be inked, means for moving print receiving material inoperative and timed relation to said member and through the printingzone, separate means for producing by electric currents a plurality ofseparate electro fields of force at the printing zone with the lines offorce of said fields of force acting in a direction to transfer ink fromthe image porto said material, and separate means movable in correlationto the movement of said material for automatically varying said currentsto vary the intensities of each of said fields of force as said materialmoves through the printing zone, whereby ink deposits of preon saidmaterial.

21. In a printing couple, a movable member having image portions adaptedto be inked, means for moving print receiving material in operative andtimed relation to said member and through the printing zone, separatemeans for producing a plurality of separate electro fields of force atthe printing zone with the lines of force of said fields of force actingin a direction to transfer ink from the image portions of said member toa master control member movable said material, and separate meansoperatively controlled by said control member for varying theintensities of each of said electro'fields of force as said materialmoves through the printing zone, whereby ink deposits of predeterminedvarying densities can be produced on said mate rial correlated to saidcontrol member.

22. In a printing couple, a movable member having image portionspermeable to lines of force and non-image portions impermeable thereto,means for moving print receiving material in operative and'timedrelationship to said member and through the printing zone by an electriccurrent, means for creating at the printing zone an electro field offorce with the lines of force thereof extending through said materialand the permeable image portions of said member but intercepted by theimpermeable portions thereof discharge and attraction elements locatedinthe printing zone on opposite sides of said material andsaid member,means for introducing ink to said field of force to be carried by thelines of force to areas of said material correlated to said imageportions of said member, and means correlated to the movement of saidmaterial for automatically varying said current to vary the intensity ofsaid field of force to produce on said material as it passes through theprinting zone ink deposits of predetermined varying densities.

23. In a printing couple, a movable member having image portionspermeable to lines of force and non-image portions impermeable thereto,

means for moving, print receiving material in operative and timedrelationship to said member and through the printing zone by electriccurrents, means for creating at the printing zone a plurality of electrofields of force with the lines of force thereof extending through saidmaterial and the permeable image portions of said member but interceptedby the impermeable portions thereof and including a plurality of sets ofspaced discharge and attraction elements located in the printing zonewith the discharge and attraction elements of each set on opposite sidesof said material and said member, means for introducing ink to saidfields of force to be carried by the lines of force to areas of saidmaterial correlated to said image portions of said member, and separatemeans acting in correlation to the movement of said material forautomatically varying said currents to vary the intensities of each ofsaid fields of force to produce on said material as it passes throughthe printing zone ink deposits of predetermined varying densities.

24. In a printing couple, a movable member having image portionspermeable to lines of force and non-image portions impermeable thereto,means for moving print receiving material in operative and timedrelationship to said member and through the printing zone, means forcreating at the printing zone an electro field of force with the linesof force thereof extending through said material and the permeable imageportions of said member'but intercepted by the impermeable portionsthereof and including spaced discharge and atti action elements locatedin opposite sides of said material and said member, means forintroducing ink to said field of force to be carried by the lines offorce to areas of said material correlated to said image portions ofsaid member, a master control member movable in timed relation to saidmovable member, means for projecting light beams onto said controlmember to be reflected thereby, light sensitive means activated by thereflected light beams, and means controlled by the degree of activationof said light sensitive means for varying the intensity of said fieldofforce in relation to the strength of the reflected light beams toproduce on said material as it passes through the printing zone inkdeposits of predetermined varying densities.

25. In a printing couple, ink carryingmeans, means for moving printreceiving material relative to said ink carrying means and through theprinting zone, a master control member movable in timed relation to themovement of said material through the printing zone, means for producingan electro field of force at the printing zonewith the lines of forcethereof acting in a direction to transfer ink from said ink carryingmember to said material, means for projecting light beams against saidcontrol member to be reflected thereby, light sensitive means activatedby said reflected light beams, and means controlled by said lightsensitive means for varying the intensity of said field of force inrelation to the strength of the reflected light beams to cause inkdeposits on said material of predetermined varying densities.

.o 26. In a printing couple, an ink carrying member, means for movingprint receiving material relative to said member and through theprinting zone, a master control member movable in timed relation to themovement of said material through the printing zone and provided withdifferent areas of predetermined color density,

the printing zone on means for producing an electro field of force atthe printing zone with the lines of force thereof acting in a directionto transfer ink from said ink carrying member to said material, andmeans for maintaining the densities of the ink deposits on'said materialcorrelated to the color densities of said areas on said control memberand including separate means for projecting light beams on said areas ofsaid control member and on saidink deposits on said material to bereflected thereby, separate light sensitive means activated by saidreflected light beams,

and means controlled by an unbalanced activation of said light sensitivemeans for varying the intensity of said field of force.

27. In a printing couple, an ink carrying member, means for moving printreceiving material relative to said member and through the printingzone, means for producing an electro field of force at the printing zonewith the lines of force thereof acting in a direction to transfer inkfrom said ink carrying member to said material and including an electriccircuit, and means for varying the intensity of the current of saidelectric circuit and hence the intensity of said field of force as saidmaterial moves through the printing zone to produce ink deposits on saidmaterial of predetermined varying density and including a master controlmember movable in timed relation to the movement of said materialthrough the printing zone and provided with switch actuating elementsarranged thereon in predetermined manner, resistance means adapted to beselectively introduced into said circuit, and switch means actuated bysaid elements for introducing said resistance means into said circuit.

28. In a printing couple, a rotatable cylinder provided with imageportions permeable to lines of force and non-image portions impermeablethereto, mearm for moving print receiving material through the printingzone and relative to said cylinder with said material supported thereby,a series of discharge blades extending transversely of said material andlocated on one side thereof at the printing zone, a series of attractionblades located within said cylinder and in the plane of said series ofdischarge blades with each attraction blade cooperating with acorrelated discharge blade to form a plurality of sets of discharge andattraction blades, means for inking said discharge blades, separatemeans for connecting each set of discharge and attraction blades with asource of high potential electric energy to induce an electrostaticfield of force between said blades with the lines of force thereofpassing through said material and the permeable image portions of saidcylinder and acting to transfer ink from said discharge blade to saidmaterial, a master control member movable in timed relation to saidcylinder and said material and provided with areas of differentpredetermined color densities, light sources for projecting light beamsonto said areas of said control member to be reflected thereby, lightsensithe print receiving tive means scanning the control member and receiving the reflected light beams and activated thereby, and meansoperatively controlled by said light sensitive means for varying theintensities of the fields of force between the sets of discharge andattraction blades to vary the densities of the ink deposits on the printreceiving material in correlation to the color densities of said areason said master control member.

29. In a printing couple as defined in claim 28 and wherein lightjecting light beams onto the ink deposits on the print receivingmaterial to be reflected thereby, while light sensitive means scan saiddeposits and receive the said reflected light beams and are activatedthereby, the light sensitive means which scan the control member and thelight sensitive means which scan the ink deposits on the materialconjunctively controlling the means which vary the intensities of theelectrostatic fields of force.

30. In a printing couple, a rotatable cylinder provided with imageportions adapted to be inked, a series of radial discharge bladesextending longitudinally within said cylinder, means for moving printreceiving material through the printing zone and in operative and timedrelation ship to said cylinder, a similar series of attraction bladeslocated in the plane of said series of discharge blades and on the sideof said material remote from said cylinder with each attraction bladecooperating with a discharge blade to form a plurality of sets ofdischarge and attraction blades, separate means for connecting each setof blades with a source or high potential electric energy to induce anelectrostatic field of force between the blades of each set with thelines of force thereof acting in a direction to transfer ink from theimage portions of the cylinder to material, a master control membermovable in timed relation to said cylinder and said material andprovided with actuating elements correlated to the sets of discharge andattraction blades and arranged on said control member in predeterminedmanner, and means actuated by said elements to vary in a predeterminedmanner the intensities of the fields of force produced by said sets ofdischarge and attraction blades to effect ink depositions on thematerial of predetermined varying densities.

WILLIAM C. HUEBNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,275,642 Bechman Aug. 13, 19181,568,651 Bryson e Jan. 5, 1926 2,152,077 Meston Mar. 28, 1939 2,183,720Lougee Dec. 19, 1939 2,224,391 Huebner Dec. 10, 1940 2,447,374 SmyserAug. 17, 1948 sources are provided for pro,- v

